Typical exterior covering materials used in modern roof construction include asphalt, wood and mineral fiber shingles and shakes. Such roofing materials are applied to decking over the framing members of a building roof structure to provide waterproofing and to give protection of the underlying structure from adverse effects due to rain and other natural elements. Similar exterior covering can be applied to the outside walls of a building, as can other materials such as siding and the like. Aesthetic appearance of the exterior roofing or wall covering materials is important, and so is long life. Replacement is a labor intensive and, thus, expensive undertaking.
The life of roofing and wall covering materials is greatly reduced by the buildup of heat in the decking between the exterior covering and the underlying insulation. This is especially a problem in hot climates, such as those of Central and Southern Florida, in which the roofs and walls are constantly exposed to intensive heating from the sun. It is therefore advantageous to provide cooling ventilation between the decking and the underlying insulation. Such ventilation is also useful in colder climates where, for example, uneven roofing temperatures can contribute to the buildup of ice dams that help speed deterioration of the roofing.
Conventional roofs are typically constructed by attaching plywood or oriented strand board decking or other sheathing material to the rafters of the roof frame. Asphalt-saturated felt is then applied in layers over the sheathing, and roofing material (rolled, shingles, or shakes) is fastened row-over-row to the plywood or oriented strand board over the felt. Conventional wall construction is similar.
To prevent heat buildup under the roofing, the space beneath the sheathing should be well ventilated. This ventilation may be provided with louver vents or an exhaust fan in an attic, but is difficult to accommodate in open-beam roof constructions, such as cathedral ceilings, where batts or rigid insulation material is placed in direct contact with the sheathing.
One prior art approach to ventilating a pitched roof, described in U.S. Pat. No. 4,254,598, employs corrugated panels nailed between a base roof structure and an overlying decking to which the shingles or other roofing material are affixed. The spaces provided by the corrugations serve as air passages for the circulation of air between the base structure and the top decking, up the roof from the eaves to the ridge. The aim of the air passages is to keep the roofing material at uniform ambient temperature to prevent the formation of ice dams in winter and the buildup of heat in the summer.
The ventilating passages provided by the corrugated structure of U.S. Pat. No. 4,254,598 do not interconnect to allow cross-ventilation between adjacent passageways at points intermediate the eaves and ridge. Further, although local temperature variations are dispersed through air circulation, no insulation material is interposed between the roofing and the base roof structure to keep out the ambient temperature. Insulation needs must, thus, be separately addressed. Moreover, the corrugated panel must be affixed to the base structure and the overlying decking applied at the building site in a two step process. The bottom of each corrugation is first nailed to the base structure and then the overlying decking is nailed to the top of each corrugation. This on-site assembly process is time consuming and, when completed, leaves an array of nail heads and possibly protruding nails exposed on the surface to tear into the overlying roofing and othrwise interfere with the roof laying process.